Hydrogen adsorption in two different metal–organic frameworks (MOFs), MOF‐5 and Cu‐BTC (BTC: benzene‐1,3,5‐tricarboxylate), with Zn2+ and Cu2+ as central metal ions, respectively, is investigated at temperatures ranging from 77 K to room temperature. The process responsible for hydrogen storage in these MOFs is pure physical adsorption with a heat of adsorption of approximately –4 kJ mol–1. With a saturation value of 5.1 wt.‐% for the hydrogen uptake at high pressures and 77 K, MOF‐5 shows the highest storage capacity ever reported for crystalline microporous materials. However, at low pressures Cu‐BTC shows a higher hydrogen uptake than MOF‐5, making Cu‐based MOFs more promising candidates for potential storage materials. Furthermore, the hydrogen uptake is correlated with the specific surface area for crystalline microporous materials, as shown for MOFs and zeolites.

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The diameter is decisive: Adsorption sites for hydrogen in the metal–organic frameworks Cu‐BTC, MIL‐53, MOF‐5, and IRMOF‐8 could be identified by using thermal desorption spectroscopy at very low temperatures (see graph). The correlation between the desorption spectra and the pore structure of these MOFs shows that at high hydrogen concentrations the diameter of the cavity determines the heat of adsorption.

Electrochemical oxidation of 2,4‐dimethylphenol directly provides pentacyclic systems being generated by an oxidative trimerization. The major pentacyclic scaffold is exclusively formed as a single diastereoisomer and is easily isolated. Three further pentacyclic compounds which occur in minor quantities were also fully characterized including their solid‐state structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Substituted phenols were anodically coupled to the corresponding 2,2'-biphenols via tetraphenoxy borate derivatives. This electrochemical method is particularly useful for methyl-substituted substrates, such as 2,4-dimethyl phenol. The selective ortho-coupling reaction can be easily performed on a multikilogram scale.